Pulse-jet engine with variable volume combustion chamber

ABSTRACT

The specification discloses a propulsion unit made up of an outer burner wall that is generally polyhedronical and/or generally conical at its forward component and generally cylindrical at its rearward end, a combustion shell concentrically disposed inside the outer burner wall and defining an annular space for combustion between them. Fuel lines are connected to feed fuel directly to the annular space. A cylindrical shell is supported around the burner wall, open at the front, to gather ram air. Flutter valves close intermittently in accordance with the spark plug sparks and/or predetermined combustion rates. The pulse jet section fuel nozzles admit fuel to the forward continuous annular generally conical combustion space forming the pulse jet section and afterburner fuel nozzles admit fuel to the more central and rearward portions of said generally annular combustion space which form the first stages of the afterburner section. An electric motor moves the inner shell relative to the outer shell to change the size of the space between them, thus regulating combustion chamber volume as required. This makes it possible to use the propulsion unit at low speeds as well as high speeds and makes possible lower as well as higher predetermined combustion rates. The combination of shells results in a multi-stage pulse jet unit and a multi-stage afterburner unit. The two units operate to provide a highly efficient jet engine, capable at its higher propulsive effort of becoming a self-propelled ram jet engine.

i United States Nov. 4, 11975 PULSE-JET ENGINE WITH VARIABLE VOLUME COMBUSTION CHAMBER [76] Inventor: Cosmo Carleton Amenta, P.O. Box

650, North East, Pa. 16428 [22] Filed: Aug. 26, 1974 21 Appl. No.: 500,445

Related US. Application Data 4 [63] Continuation-impart of Ser. No. 281,640, Aug. 18,

1972, abandoned. I

52 US. Cl. 60/244; 60/247; 60/262; 60/270 R [51] Int. Cl. F02K 7/06 [58] Field of Search 60/244, 247, 248, 249,

[56] References Cited UNITED STATES PATENTS 2,675,196 4/1954 Marnay 60/248 X 2,683,961 7/1954 Britton et'al 60/247 2,705,396 4/1955 Boyce et a1. 60/248 3,307,355 3/1967 Bahr 60/267 X 3,514,957 6/1970 Evans 60/270 3,517,510 6/1970 Melenric 60/249 Primary Examiner-Carlton R. Croyle Assistant Examiner-Robert E. Garrett ABSTRACT The specification discloses a propulsion unit made up of an outer burner wall that is generally polyhedronical and/or generally conical at its forward component and generally cylindrical at its rearward end, a combustion shell concentrically disposed inside the outer burner wall and defining an annular space for combustion between them. Fuel lines are connected to feed fuel directly to the annular space. A cylindrical shell is supported around the burner wall, open at the front, to gather ram air. Flutter valves close intermittently in accordance with the spark plug sparks and/or predetermined combustion rates. The pulse jet section fuel nozzles admit fuel to the forward continuous annular generally conical combustion space forming the pulse jet section and afterburner fuel nozzles admit fuel to the more central and rearward portions of said generally annular combustion space which form the first stages of the afterburner section. An electric motor moves the inner shell relative to the outer shell to change the size of the space between them, thus regulating combustion chamber volume as required. This makes it possible to use the propulsion unit at low speeds as well as high speeds and makes possible lower as well as higher predetermined combustion rates. The combination of shells results in a multistage pulse jet unit and a multi-stage afterburner unit. The two units operate to provide a highly efficient jet engine, capable at its higher propulsive effort of becoming a self-propelled ram jet engine.

6 Claims, 4 Figures US. Pa an? Nov. 4, 1975 3 m2 i! Q mu .IL 9w PULSE-JET ENGINE WITH VARIABLEVOLUME COMBUSTION CHAMBER REFERENCE TO CO-PENDING APPLICATION This application is a Continuation-in-part application of U8. Pat. application, Ser. No. 281,640, filed Aug. 18, 1972, and now abandoned.

' STATEMENT OF INVENTION OBJECTS OF THE INVENTION It is an object of the invention to provide a propulsion unit which will operate on the jet principle which is efficient at low speeds, as well as at high speeds.

Another object of the invention is to provide an improved jetpropulsion unit which includes a propelling jet forming nozzle structure and related structure.

'Another object of the invention is to provide an improved multistage afterburner combination and improved ram jet combination.

Another object of the invention is to provide an improved multistage pulse jet system or combination in combination with an improved ram jet system or combination.

Another object of the invention is to provide an improved multistage pulse jet in combination with an improved multistage afterburner combination which comprise "an improved self-propelled ram jet system.

pulse jet combination with a multistage afterburnerwhich will operate with maximum efficiency.

Another object of the invention is to provide a ram jet in combination with a pulse jet and fuel preheating means for use by the respective combinations of the system.

Yet another object of the invention is to provide a propulsion unit comprising a fluid compressing means forming a passage connection, the discharge of the pulse jet passing adjacent walls of a passage for preheating fuels for combustion in the pulse jet combination and afterburner unit.

Another object of the invention is to provide a propulsion unit comprising a fluid compressing means forming a passage connection, the discharge of the afterburner primary stages passing adjacent walls of a passage for preheating fuels for combustion in the pulse jet combination and/or afterburner unit as predetermined.

Another object of the invention is to provide an improved jet propulsion unit which includes the combination of a multistage pulse jet for preheating fuel to be used by the pulse jet unit.

Another object of the invention is to provide 'an improved jetpropulsion unitwith the combination of a multistage afterburner unit for preheating fuel to be used by the afterburner unit.

Another object of the invention is to provide a jet propulsion unit which includes means for compressing fluid and means for forming a passage connection for hot gases and means for preheating fuel for combustion in a multistage pulse jet combination unit and afterburner combination unit with nozzle means connecting the exhaust of the multistage pulse jet unit to the exhaust of the afterburner unit.

Another object of the invention is to provide an improved jet propulsion unit which includes a multistage pulse jet in combination with means to direct highly heated exhaust gases and means for preheating the fuel to be used, as predetermined, in the multistage pulse combination.

Another object of the invention is to provide an improved jet propulsion unit which includes a multistage afterburner unit or combination, in combination with means to direct highly heated exhaust gases and means for preheating the fuel to be used, as predetermined, in the multistage afterburner combination.

Another object of the invention is to provide an improved combination pulse jet and afterburner with means to adjust the volume of the combustion chamber of the pulse jet, as predetermined.

Another object of the invention is to provide an improved combination pulse jet and afterburner with means to adjust the volume of air for combustion of the combustion chamber of the afterburner, as predetermined.

Another object of the invention is to provide an improved pulse jet.

Another object of the invention is to provide an improved afterburner system.

Another object of the invention is to provide an improved self-propelled ram jet system.

With the above and other objects in view, the present invention consists of the combination and arrangement of parts hereinafter more fully described, illustrated in the accompanying drawings and more particularly pointed out in the appended claims, it being understood that changes may be made in the form, size, proportions, and minor details of construction without departing from the spirit or sacrificing any of the advantages of the invention.

GENERAL DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal cross sectional view of the propulsion unit according to the invention.

FIG. 2 is a longitudinal cross-sectional view taken on line 2-2 of FIG. 1. I

FIG. 3 is an enlarged partial cross-sectional view of the valve according to FIG. 1'.

FIG. 4 is a longitudinal'ctoss-sectional view taken on line 4-4 of FIG. 1.

DETAILED DESCRIPTION. OF THE DRAWINGS Now with more particular reference to the drawings, the multi-stage propulsion unit shown is made up of several shells supported concentric to and generally uniformly spaced from each other. These shells provide spaced annular passages between them for air combustion space and hot gases.

Shell A, or the inner combustion shell, is generally cylindrical in shape from its forward to its rearward end, but whose construction tapers to a generally conical end at the front, forms the inner surface of the forward end of the combustion chamber and is coaxially disposed with regard to tube 41 which provides means for, air passage. The inner shell A is slidably attached to intermediate shell B and may be moved forwardly or rearwardly axially relative to shell B to predetermined 3 positions to change the cross sectional area ofthecom! bustion passage 11 between the inner shelllA and the outer burner wall B by means of the motor M2 which drives jack screw 8 which threadably engages the nut 9.

, The inner shell B and the outerburner-wall B define an 1 annular passage between them in which the hot gases around the jack screw 8 and nut 9 throughthe passage 56 and out the exits 43 and 43A to cool the motors M2 and M3. Shell A supports several rows of fuel injection nozzles 31 and several rows of spark plugs 34 arranged on the inside of the inner shell A, Shell A also contains preheat coils 30 and fuelline 27. a

. Shell B is generally polyhedronical and/or generally conical in shape from its forward .to its rearward end, but tapers to a generally conical end at the front. It is supported concentric .to and generally uniformly spaced from shell A. Shell B forms the outer surface of the forward end of the combustion chamber and confrusto-conical outside surface which is attached to the shaft of motor system M1 and slides upon shell The drum acts as a valve which moves relative to shell B and shell .C since the inside diameter of shell C decreases toward the outlet end and it closes the openings 46, 58 and 61in shell C when it is moved rearward and valve 511 opens openings 46, 58 and 61 when it moved forward to the dashed line position 50. Valve 50 has a passage 51 which conducts air from inlet 19 to cool motor M1 when valve 50 is closed. That is, the'ou'ter shell B co-acts ,with theinner shell A to form,bet ween them a high temperature fluid passage 38 connectedto the discharges of the multi-stage pulse jet combination unit. Shell B supports the several fuelnozzles49 of the afterburner combination unit 53. Shell B also contains opening 58 from passage 37. v I

disposed concentrically about shell B. It has a forward end 19 which defines an access to air passage 57 between shells 'B and C which allows air to the flutter valves 20.,Shell C alsoadmits air from passages 25 to afterburner 53 through opening 46 at the slide valve 1 mechanism 50.

Shell D is an intermediate generally conical shell which contains a forward end which defines an air inlet which admits air to passage formed by shellsC and D which terminates at the slide valve mechanism 50 at opening 46.

Shell is a generally conical shell containing a forward 4 Shell F is an outer generally conical shell which contains forwarden d l3 which defines an. air inlet which admits air to passage 39km provide cooling air for the tail' w'all', and also provides additional air for the final combustion in'the exhaust nozzle 55. The shell F basicallyforms the casingthat is supported on-the frame or shell of the propelledvehicle by means of a structural Shell C is an intermediate generally cylindrical shell 1- end 22 which defines an air inlet which admits air toithe passage 45 formed by shells D and E and directs .air-

through opening 61 to the afterburner 53 and out the final exhaust-passage 55. Shells]? and B form passage 37 which allows incoming air from passage 45 to flow to exhaust 55.

" end 22 of-"shell-Eadmits member 42 which is attached to the outer shell F by means of supports 47 which pass through a flange 44 and rigidly support the propulsion unit. The hollow duct v29 receives thefuel lines 27 and 28 and ignition wires 33 and controljlines 32, connecting them to suitable fuel tanks and electrical systems. i I I T he forw ard facing airinlet 40, whose construction is a conical cylindrical form from its forward to its rearward end, is located at the forward end of the multistage combination un it. Air inlet 40 receives the central cooling' duct 41, which provides means for air passage.

Central cooling duct 41 is supported concentric to and generally uniformly spaced frorn an inner cylindrical shell A Air inlet 40 directs air through the tube 41 .around the jack screwl8 and nut 9, through the' passage 5,6to co0l the motors M2 and M3,;and out the exits 43 a 4 and y h the av The forward facing air inlet formed by the forward end .19 of the cylindrical outer shell C which allows air through the passage 57 to the flutter valves 20 in shell Ram air is picked up at forwardlyfacing ram inlet at 19 and it passes back through the flutter valves 20 that are familiar to those skilled in the art, which extend to various .p ositionsias illustrated at openings 21 The flutter valves 20 admit airto combustion passage 11 which lies between shells A and B. The'cornbustion chamber 11 defines aa nmnar f ssage-i whichfthe hotgases burn and drive rearwa rdly The air str e'am entering chamber llf'at y'alves 20 has" fuelinjected into b fuel nozzles 31. This rnixtur.e of-air and fuel burnsin channel 1 1 and channel 38 andpasses-onfinto theexhaust Shells A and'B form the annularpassage 38 which he ats the exhaust forming gas flowing in th e chamber from the multi-stage pulsejetcombination unit 51. The passage Q38 communicates into rearwardly directed nozzle 54 arid exhaust 55. Outer shells A and B support fuel nozzles'4 9 of the afterburner combination unit 53.

The forward facing airinlet-IS admits air throughthe passages 25, through the openings 46; 58 and '61 when valve 50 is moved'to' the dashed line position into the space between the intermediate shell and shell C. The. valvefsystem 501s in 'the form of an annular drum having 'a tapered outer surface. The valve is attached to motors system Ml supportedori'shell B. The drum acts as a valve which moves relative'to shell B and closes the openings 46, 5S and 61 ThatiSQ the outer shell B 00-- acts with the innerishe ll A to'for'mbetwee'nthem ahigh temperature. fluid passage .38 connected to the discharges of the multi-st ag e pulse jet combination unit 51. The multi-stag 'aft erburner combination unit 53, whose major assembly is on the outer side of shell A, forms passages 37 and 3 8j which exhaust into nozzle 54 and then communicates the final exhaust passage 55. .Motorfsystem is'cooled by air through opening 69 and duct 68. l

I The forward facing air inletlformed by the forward to thepassage 45'formed by shells D and: E whicli is controlled. by the slide valve moved forwardly and rangement. From openings 46, 58 and 61 the air then passes through an afterburner air entry 24 thro ugh the channels 37 and 38 and out final exhaust passage 55.

The forward facing air inletformed by the forward end 13 of shell F, which admit s cooling air .to the passage 39 formed by shells Band P which communicates through opening 23 to the afterburner 53 and out the final exhaust passage 55. The air in passage 39 cools the tail wall and provides additional air for the final combustion in the exhaust. nozzle 55.

The multi-stage afterburner combination unit 53 has fuel nozzles 49 to inject fuel into the passages 37 and 38 which heat the exhaust forming gas flowing in the chamber from the multi-stage pulse jet combination 51.

The multi-stage pulse jet combination unit 51 has the fuel injectors 31 and spark plugs 34 arranged in .combustion chamber 11. .Ram ,air is introduced through flutter valves,20 that-.arefamiliar to those skilled in the art, which extend to various positions as illustrated at openings21..

The motor M2 drives a shaft 8 which threadably engages the nut 9 and moves the inner shell A forwardly or rearwardly to change the cross sectional area of the combustion passage 11 which lies between shells A and B.

The motor system M1 is threadably attached to a jack screw arrangement which opens and closes the openings 46, 58 and 61 by moving annular drum or valve system 50. This adjustment takes place as predetermined.

The hollow duct 29 receives the annular fuel lines 27 and 28, and the control line 32, and ignition wires 33,

connecting them to suitable fuel tanks and electrical systems. The fuel from line 27 flows through the reheat coils 30 which are coiled about the inner periphery of the inner shell A, to the fluid fuel injection elements 31 which inject fuel into the combustion space 11. This fuel from injection points 31 is ignited by spark plugs 34 and hot gas passes back toward the afterburner and out the exhaust 55. The fuel from line 28 is pre-heated in the coils 17 that extend around the outer periphery of the multi-stage combination unit 51. From the coils 17, the fuel is passed through fuel injectors 49 into passages 38, 54 and 55. The structural member 42 rigidly supports the propulsion unit on the wing of an aircraft or the like by means of supports 47 which pass through a flange 44 at the lower end of member 42 and through the casing 14 of the unit which is located generally around the outer shell F and forms the outer enclosure of the propulsion unit.

In operation, the air entering intake 19 through flutter valves 20 is subjected to compression and contrac tion in the explosion pulses as the valves flutter, as the air is heated and moves rearwardly. The passage 11 terminates in final passages 38 and 54 which converge into an exhaust nozzle portion 55 where final combustion takes place. If need be, the nozzle structure 55 can be further cooled to withstand the high temperatures.

It will be seen that when the aircraft or propelled vehicle is not in flight and is stationary, air will be drawn into the opening 19 through the flutter valves 20 and be burned in the space 11 between the intermediate shell B and inner shell A. Fuel will be introduced from fuel line 27 and through coil 30 into this space and will be ignited by several spark plugs 34 which are supported in the inner shell A in rows on the inner shell A. Several fuel injection nozzles 31 are also supported on the inner shell A in rows.

As the vehicle on which th e engine is mountedpgmes up to speed, the clearance between shell AandsheII B may be changed to take advantage of the. ram air entering between the shells C and B at the entrance 19.

i As the vehicle comes further up to speed, ram air entering at 19, and also ram air entering at 15, is controlled by motor system M1 which actuates the sliding valve system 50 forward, opening the passages 46, 58 and 61 'and allowing ram air to enter the chamber through passages 39 and 45 and passage 25', to throttle the air entering the afterburner space. Air entering at 13 passes rearwardly through passage 39 and enters the afterburner throughopenings' 23 and 58 just ahead of the exhaust'passage 55 to completethe combustion.

When considering the multi-stage'pulse and combustion combination unit and multi-stage afterburner combination unit, it must be borne in mind that within practical temperature limits, the higher the temperature the gas can reach in the propulsion unit, the greater the efficiency of the unit. consequently in order to obtain maximum thermal efficiency of the'combination disclosed, it is necessary to operate under conditions af fecting the highest permissable inlet temperatures of the multi-stage pulse jet combustion and highest inlet temperatures of the exhaust means of the same multistage unit. It is also necessary to operate under conditions affecting the highest permissable inlet temperatures of the afterburner combination unit. This more efficient system combination provides an efficient and self-propelled ram jet system.

The foregoing specification sets forth the invention in its preferred practical forms but the structure shown is capable of modification within a range of equivalents without departing from the invention which is to be understood is broadly novel as is commensurate with the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A jet propulsion unit comprising, 1

a generally cylindrical outer burner wall being tapered inward toward the inlet end and generally conical in shape,

an inner combustion shell disposed in said outer burner wall and being of a similar shape and disposed inside said outer burner wall and defining an annular chamber therebetween,

spaced air intake scoops in the outer periphery of said outer burner wall,

means to supply fuel to said annular space,

and spark means adjacent the inlet end of said annular chamber, electrical means for applying a high tension current to said spark means whereby said fuel is ignited,

and means to move said inner burner wall selectively toward and away from said inlet whereby the inlet to said combustion chamber and the size of the space making up said combustion chamber is regulated,

openings are formed in said outer burner wall and flutter valves are supported on said outer burner wall and adapted to intermittently close said openings when the pressure in said space decreases below a predetermined value.

2. The unit recited in claim 1 wherein said electrical means comprises an induction coil having means to connect an intermittent current to said spark means at '7v a predetermined frequency.

3. The unit recited in claim 2 wherein a vane shell is disposed around said burner wall,

said vane shell being generally cylindrical in shape, open at the front, and defining an intake for air and defining a space between said outer burner wall,

and fuel nozzles extending into said space between said outer burner wall and said vane shell adjacent the rear end thereof.

4. The unit recited in claim 1 wherein means to move said outer burner wall and said combustion shell relative to each other comprises motor means fixed to said outer burner wall and to said combustion shell whereby said outer burner walland said shell are moved relative to each other, 7

a path for cooling air is formed in said unit whereby cooling air is directed around said motor means and through said motor means.

5. In a combination pulse and ram jet, said pulse jet comprising two concentric generally cylindrical members defining a combustion chamber therebetween defined by a first generally cylindrical shell, and a second 8 generally cylindrical shell inside said first cylindrical shell defining a continuous annular combustion space, means to move said first shell relative to said second shell to decrease said space adjacent the inlet end thereof between said shells, flutter valves on said second shell for admitting air into said space, means to inject fuel into said space, and means to ignite said fuel, and a third shell generally concentrically disposed around said second shell and providing structure for and inclusive of ram air ducts, means to feed ram fuel into the ram air ducts, and valve means for shutting off the flow of air through said ram air ducts. 6. The combination recited in claim 5 wherein an annular valve member is connected to said burner wall,

openings in said outer burner connecting said ram space to said burner space, said valve member being adapted to close said openings connecting said ram space to said burner space. 

1. A jet propulsion unit comprising, a generally cylindrical outer burner wall being tapered inward toward the inlet end and generally conical in shape, an inner combustion shell disposed in said outer burner wall and being of a similar shape and disposed inside said outer burner wall and defining an annular chamber therebetween, spaced air intake scoops in the outer periphery of said outer burner wall, means to supply fuel to said annular space, and spark means adjacent the inlet end of said annular chamber, electrical means for applying a high tension current to said spark means whereby said fuel is ignited, and means to move said inner burner wall selectively toward and away from said inlet whereby the inlet to said combustion chamber and the size of the space making up said combustion chamber is regulated, openings are formed in said outer burner wall and flutter valves are supported on said outer burner wall and adapted to intermittently close said openings when the pressure in said space decreases below a predetermined value.
 2. The unit recited in claim 1 wherein said electrical means comprises an induction coil having means to connect an intermittent current to said spark means at a predetermined frequency.
 3. The unit recited in claim 2 wherein a vane shell is disposed around said burner wall, said vane shell being generally cylindrical in shape, open at the front, and defining an intake for air and defining a space between said outer burner wall, and fuel nozzles extending into said space between said outer burner wall and said vane shell adjacent the rear end thereof.
 4. The unit recited in claim 1 wherein means to move said outer burner wall and said combustion shell relative to each other comprises motor means fixed to said outer burner wall and to said combustion shell whereby said outer burner wall and said shell are moved relative to each other, a path for cooling air is formed in said unit whereby cooling air is directed around said motor means and through said motor means.
 5. In a combination pulse and ram jet, said pulse jet comprising two concentric generally cylindrical members defining a combustion chamber therebetween defined by a first generally cylindrical shell, and a second generally cylindrical shell inside said first cylindrical shell defining a continuous annular combustion space, means to move said first shell relative to said second shell to decrease said space adjacent the inlet end thereof between said shells, flutter valves on said second shell for admitting air into said space, means to inject fuel into said space, and means to ignite said fuel, and a third shell generally concentrically disposed around said second shell and providing structure for and inclusive of ram air ducts, means to feed ram fUel into the ram air ducts, and valve means for shutting off the flow of air through said ram air ducts.
 6. The combination recited in claim 5 wherein an annular valve member is connected to said burner wall, openings in said outer burner connecting said ram space to said burner space, said valve member being adapted to close said openings connecting said ram space to said burner space. 